Most state-of-the-art handportable telephones are configured to send and receive short text messages, i.e. so-called SMS (Short Message System) messages. While such short messages are popular for various private purposes, the still increasing prevalence of handportable cellular telephones has led to an increase in dissemination of spam messages. Accordingly, one of Europe's largest network providers has proposed a white listing system, in which approved parties are entered on a white list and senders of spam messages are entered on a black list, so that spam providers are identifiable by the recipients of the messages.